Incision unit to manufacture a single-dose break-open package

ABSTRACT

A unit for the incision of a strip made of a plastic material to cut two distinct incisions into two opposite surfaces of the strip; the incision unit has: a conveying device, which feeds the strip along a conveying direction; two support plates, which are arranged on opposite sides of the strip, so that each support plate faces a corresponding surface of the strip; and at least two incision devices, each of which cuts an incision into a corresponding surface of the strip and has a cutting element, which is supported by a support plate, and a contrast element, which is supported by the other support plate.

FIELD OF THE ART

The present invention relates to an incision unit for a packagingmachine for single-dose break-open packages.

BACKGROUND

A sealed single-dose break-open package normally consists of a sheetmade of a semirigid plastic material and of a sheet made of a flexibleplastic material arranged on top of and sealed to each other in order todefine a sealed pocket containing a dose of product; the semirigidplastic material sheet centrally has an incision which guides acontrolled breaking of the semirigid plastic material sheet. In use, inorder to open the package, a user simply needs to grip the packageitself with his/her fingers and bend the package until the semirigidplastic material sheet breaks at the incision.

Patent application WO2008038074A1 suggests a packaging machine whichmanufactures sealed single-dose break-open packages. In such a packagingmachine, a strip made of a semirigid plastic material and a strip madeof a flexible plastic material are unwound from respective reels and fedto a forming station. A pattern is printed on the outer surface of thesemirigid plastic material strip and an incision is cut into thesemirigid plastic material strip upstream of the forming station; inparticular, two incisions are cut at different times (i.e. notsimultaneously) into the opposite surfaces of the semirigid plasticmaterial strip, which incisions are opposite and aligned by means of twoincision devices arranged one next to the other in the conveyingdirection of the semirigid plastic material strip. After that, thesemirigid plastic material strip and the flexible plastic material stripare arranged on top of each other in the forming station and then sealedin a longitudinal sealing station in order to define a tube adapted tocontain the product. A dosing device is arranged at the longitudinalsealing station to feed the product between the two strips which werelongitudinally sealed. A transversal sealing station is arrangeddownstream of the longitudinal sealing station to perform a transversalsealing so as to close the pocket of each sealed single-dose package.Finally, a cutting station is arranged downstream of the transversalsealing station, where the two strips are cut transversely so as toseparate, in sequence, the sealed single-dose packages.

However, it has been noted that, when operating at high speed in theabove-described packaging machine, the incision of the semirigid plasticmaterial strip not always has an optimal quality (in particular, the twoincisions cut into the opposite surfaces of the semirigid plasticmaterial strip are not always perfectly aligned to each other).

It is the object of the present invention to provide for an incisionunit for a packaging machine which manufactures a single-dose break-openpackage, which incision unit is free from the above-described drawbacks,and in particular is easy and cost-effective to be implemented.

According to the present invention, an incision unit to manufacture asingle-dose break-open package is provided as defined in the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to theaccompanying drawings, which show a non-limiting embodiment thereof, inwhich:

FIG. 1 shows a top perspective view of a sealed single-dose break-openpackage;

FIG. 2 shows a bottom perspective view of the package in FIG. 1;

FIG. 3 shows a cross-section of a semirigid plastic material sheet ofthe package in FIG. 1;

FIG. 4 shows a diagrammatic perspective view, with parts removed forclarity, of a packaging machine manufactured according to the presentinvention for producing the package in FIG. 1;

FIGS. 5-8 are four diagrammatic top views, with parts removed forclarity, of an incision unit of the packaging machine in FIG. 4 duringfour different operation moments;

FIG. 9 is a diagrammatic section view, with parts removed for clarity,of a printing unit of the packaging machine in FIG. 4; and

FIG. 10 is a diagrammatic perspective view, with parts removed forclarity, of a dosing unit of the packaging machine in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

In FIGS. 1 and 2, reference numeral 1 indicates as a whole a sealedsingle-dose break-open package. Package 1 comprises a sheet 2 made of asemirigid plastic material and rectangular in shape, and a sheet 3 madeof a flexible plastic material, which is arranged on top of and sealedto the semirigid plastic material sheet 2 in order to define a sealedpocket 4 containing a dose of a fluid product 5. By way of example, thefluid product 5 could be a sanitizing gel.

The semirigid plastic material sheet 2 centrally has a pre-weakened zone6 which guides a controlled breakage of sheet 2 so as to determine theformation of an outlet opening for product 5 through sheet 2. In otherwords, in use, in order to open package 1 a user needs to grip package 1with his/her fingers and bend package 1 until the semirigid plasticmaterial sheet 2 breaks at the pre-weakened zone 6.

As shown in FIG. 3, the pre-weakened zone 6 comprises an internalincision 7 which is cut through an inner surface 8 (i.e. facing pocket4) of the semirigid plastic material sheet 2 and an outer incision 9which is cut through an outer surface 10 of the semirigid plasticmaterial sheet 2. According to a preferred embodiment, each incision 7or 9 is of variable depth along its length so as to determine aprogressive breaking of the semirigid plastic material sheet 2; inparticular, each incision 7 or 9 has a maximum depth at a centralportion.

In FIG. 4, reference numeral 11 indicates as a whole a packaging machineto produce sealed single-dose packages 1 similar to that described aboveand shown in FIGS. 1 and 2. The packaging machine 11 shown in FIG. 4produces three sealed packages 1 at a time, i.e. operates in parallel onthree adjacent tracks to produce three sealed packages 1 at a time;according to other variants (not shown), the packaging machine 11 couldobviously operate in parallel on a different number of tracks arrangedone next to the other (e.g. two, four, six tracks but also a singletrack).

The packaging machine 11 (shown in FIG. 4) comprises a frame (not shown)resting on the floor by means of a plurality of resting feet (not shown)and supports a pair of unwinding devices 12 and 13. The unwinding device12 supports a reel 14 from which it progressively unwinds a strip 15 ofsemirigid (yet elastically deformable) plastic material which is fed toa forming station 16, and the unwinding device 13 supports a reel 17from which it progressively unwinds a strip 18 made of a flexibleplastic material which is also fed to the forming station 16.

A printing unit 19 is arranged between the unwinding device 12 of thesemirigid plastic material strip 15 and the forming station 16, wherethe outer surface 10 of the semirigid plastic material sheet 2 isprinted.

An incision unit 20 is arranged downstream of the printing unit 19 andupstream of the forming station 16, and transversely cuts the semirigidplastic material strip 15 in order to define the incisions 7 and 9 atthe pre-weakened zone 6 along the semirigid plastic material strip 15.

According to a preferred embodiment, the semirigid plastic materialstrip 15 is continuously fed through the incision unit 20; to this end,the incision unit 20 comprises a conveying device 21 provided with apair of feeding dandy rollers 22. The feeding dandy rollers 22 aremovable against the action of elastic means to allow the semirigidplastic material strip 15 to temporarily stop inside the incision unit20.

As shown in FIG. 4, the semirigid plastic material strip 15 providedwith the incisions 7 and 9 is then fed to the forming station 16, whichis arranged downstream of the incision unit 20 and where the semirigidplastic material strip 15 is arranged on top of and sealed to theflexible plastic material strip 18.

The two strips 15 and 18 arranged one on top of the other are sealed toeach other by means of a longitudinal roller sealing device 23 whichperforms a longitudinal sealing (both laterally and centrally), i.e.parallel to a conveying direction, so as to define a plurality of tubesarranged one next to the other. In the embodiment shown in FIG. 4, thelongitudinal sealing device 23 comprises two twin sealing assembliesarranged one on top of the other, each of which has a contrast roller 24and four sealing rollers 25 which are electrically heated and spacedapart from one another.

A dosing unit 26 to feed a dose of product 5 into each tube between thesemirigid plastic material strip 15 and the flexible plastic materialstrip 18 is arranged in the forming station 16 and at the longitudinalsealing device 23. The dosing unit 26 comprises three twin feeding ducts27, each of which is vertically arranged between two sealing rollers 25of the longitudinal sealing device 23 and feeds the doses of product 5between the semirigid plastic material strip 15 and the flexible plasticmaterial strip 18.

Finally, the forming station 16 comprises a transversal roller sealingdevice 28, which is arranged downstream of the longitudinal sealingdevice 23 and transversely seals together the two strips 15 and 18 inorder to define a series of pockets 4 (shown in FIG. 1) along each tube,each of which contains a dose of product 5. According to a preferredembodiment, the transversal sealing device 28 comprises a contrastroller 29 and a sealing roller 30, which is electrically heated andcooperates with the contrast roller 29.

Finally, a cutting device 31 is arranged downstream of the formingstation 16 so as to cut transversely the strips 15 and 18 arranged oneon top of the other and sealed so as to separate in sequence the sealedsingle-dose packages 1. An outlet conveyor belt 32 is arranged under thecutting device 31, on which the sealed single-dose packages 1 fall bygravity once they have been separated from the strips 15 and 18 arrangedon top of and sealed to each other.

The flexible plastic material strip 18 is normally pre-printed, whereas,as previously said, the semirigid plastic material strip 15 is printedinside the packaging machine 11 by using the printing unit 19; accordingto an alternative embodiment, the printing unit 19 is not present (or isdisabled), therefore the semirigid plastic material strip 15 is alsopre-printed (or without prints). The flexible plastic material strips 15and/or 18 are generally provided with reference notches, which are readby special optical sensors to synchronize the several operationsappropriately, so that the printed zones are correctly centered in thefinished sealed single-dose packages 1. The reference notches arepreferably printed in the zones of strips 15 and/or 18 which arediscarded by the cutting device 31 so as not to be present in thefinished sealed single-dose packages 1.

As shown in FIG. 9, the printing unit 19 of the semirigid plasticmaterial strip 15 comprises a conveying device 33 (diagrammaticallyshown) which feeds the semirigid plastic material strip 15 along a(substantially vertical) conveying direction C, and a printing device 34arranged in a fixed position along the conveying device 33 and facingthe outer surface 10 of the semirigid plastic material strip 15 so as toprint a pattern on the strip 15 itself. The printing device 34 is a heattransfer printing device and comprises a printing head 35, which ismovable perpendicularly to the conveying direction C along a printingdirection S so as to contact the semirigid plastic material strip 15; inother words, in use, the printing head 35 is movable along the printingdirection S, which is orthogonal to the conveying direction C andorthogonal to the semirigid plastic material strip 15 so as to come intocontact with the outer surface 10 of the semirigid plastic materialstrip 15. Therefore, in use, the printing head 35 contacts the semirigidplastic material strip 15 with a given pressure so as to print a patternon the semirigid plastic material strip 15.

The printing device 34 further comprises a fixed contrast plate 36 (i.e.in a fixed position), which is independent and separate from theconveying device 33, is arranged in a fixed position along the conveyingdevice 33, and is arranged parallel to and facing the printing device 34so that the semirigid plastic material strip 15 is arranged between thecontrast plate 36 and the printing device 34. When the printing head 35moves towards the semirigid plastic material strip 15, the printing head35 presses the semirigid plastic material strip 15 against the contrastplate 36 and therefore the printing head 35 may exert a given pressureon the outer surface 10 of the semirigid plastic material strip 15,which pressure is required to carry out the printing process properly.

The contrast plate 36 comprises a plurality of nozzles 37, each of whichopens up onto the semirigid plastic material strip 15 and is adapted torelease a compressed air blow. In particular, each nozzle 37 consists ofa through hole, which is obtained through the contrast plate 36 andreceives the compressed air by means of a pipe 39 connected to acompressed air source 40. The compressed air blown by the nozzles 37creates a pressurized air cushion 38 at the inner surface 8 of thesemirigid plastic material strip 15, which inner surface 8 is oppositeto the outer surface 10 and thus opposite to the printing device 34. Theair cushion 38 thus made creates a deformable contrast which allows theprinting head 35 to create a constant and even pressure against theouter surface 10 of the semirigid plastic material strip 15; in otherwords, the air cushion 38 is deformed in a variable and dynamic mannerso as to adapt perfectly to the shape of the printing head 35, thusensuring a completely even contact between the printing head 35 and theouter surface 10 of the semirigid plastic material strip 15. In summary,the contrast plate 36 comprises a plurality of nozzles 37, which open uponto the inner surface 8 of the semirigid plastic material strip 15 andare adapted to release a compressed air blow to create the pressurizedair cushion 38 at the inner surface 8 of the semirigid plastic materialstrip 15, opposite to the printing device 34; the air cushion 38 forms adeformable contrast against which the printing head 35 pushes thesemirigid plastic material strip 15. Thereby, the printing head 35 mayoperate under the most favorable conditions allowing a high qualitypattern to be obtained in very short times (i.e. also when the packagingmachine 11 operates at high speed).

According to a preferred embodiment, in order to maximize theeffectiveness of the contrasting action of the air cushion 38, thecompressed air is fed to the nozzles 37 with a pressure from 2 to 6 bar(preferably from 3 to 5 bar).

According to an alternative embodiment (not shown), the printing device34 may use a printing technology other than heat transfer (e.g. it mightuse ink-jet); in this case, the printing head 35 is fixed (i.e. does nottranslate perpendicularly to the semirigid plastic material strip 15).

As shown in FIG. 4, the incision unit 20 cooperates with the conveyingdevice 21 which feeds the semirigid plastic material strip 15 along theconveying direction C. The incision unit 20 comprises two support plates41, which are arranged along the conveying device 21 downstream of thefeeding dandy rollers 22 so that the feeding dandy rollers 22 cyclicallyallow the semirigid plastic material strip 15 to temporarily stopbetween the two support plates 41. The two support plates 41 arearranged on opposite sides of the semirigid plastic material strip 15;therefore, each support plate 41 faces a corresponding surface 8 or 10of the semirigid plastic material strip 15.

As shown in FIGS. 5-8, the incision unit 20 is provided with sixincision devices 42, each of which cuts an incision 7 or 9 (shown inFIG. 3) into a corresponding surface 8 or 10 of the semirigid plasticmaterial strip 15; in particular, three incision devices 42 a, which arearranged one next to the other, cut respective inner incisions 7 intothe inner surface 8 of the semirigid plastic material strip 15 and threeincision devices 42 b, which are arranged one next to the other, cutrespective outer incisions 9 into the outer surface 10 of the semirigidplastic material strip 15. Each incision device 42 comprises a cuttingelement 43 supported by a support plate 41 and facing the correspondingsurface 7 or 9 of the semirigid plastic material strip 15, and acontrasting element 44 supported by the other support plate 41 andfacing the corresponding surface 9 or 7 of the semirigid plasticmaterial strip 15. Each cutting element 43 is provided with a blade (notshown in detail) which is preferably V-shaped; in contrast, eachcontrast element 44 is flat so as to provide the blade of thecorresponding cutting element 43 with an even contrast.

The two support plates 41 are mechanically connected together so as tomove synchronously along a translation direction T which is orthogonalto the conveying direction C; in particular, the two support plates 41are mounted so as to be movable on corresponding rails 45 so as totranslate (slide) together along the translation direction T, which isorthogonal to the conveying direction C. In other words, the two supportplates 41 are provided with corresponding slides, which are slidinglycoupled to the rails 45 so as to translate (slide) along the translationdirection T under the control of an actuating device 46 (e.g. of theelectric or pneumatic type). The six incision devices 42 are arrangedone next to the other and are aligned along the translation direction T.The actuating device 46 cyclically moves the two support plates 41forward and backward along the translation direction T between a firstposition (shown in FIGS. 5 and 6), in which the incision devices 41 acut the inner incisions 7 into the inner surface 8 of the semirigidplastic material strip 15, and a second position (shown in FIGS. 7 and8), in which the incision devices 41 b cut the outer incisions 9 intothe outer surface 10 of the semirigid plastic material strip 15.

Each support plate 41 supports the cutting elements 43 of an incisiondevice 42 a or 42 b and the contrast elements 44 of the other incisiondevice 42 b or 42 a; in other words, each support plate 41 supports boththree cutting elements 43 and three contrast elements 44.

A support plate 41 is movably mounted on corresponding rails 47 so as totranslate (slide) cyclically forward and backward towards the othersupport plate 41 and along an incision direction I, which is orthogonalto both the conveying direction C and the translation direction T. Inother words, a support plate 41 is provided with corresponding slideswhich are slidingly coupled to the rails 47 so as to translate (slide)along the incision direction I under the control of an actuating device48 (e.g. of the electric or pneumatic type).

In a preferred embodiment shown in the accompanying figures, eachincision device 42 comprises an adjusting organ 49 (e.g. a micrometer)to adjust the depth of incision 7 or 9 by varying the relative positionbetween the corresponding cutting element 43 or the correspondingcontrast element 44 and the respective support plate 41. Each adjustingorgan 49 is coupled to the cutting element 43 or to the contrast element44 of the same incision device 42 and is adapted to adjust the distancebetween the cutting element 43 or the contrast element 44 and thesemirigid plastic material strip 15.

In a preferred embodiment shown in the accompanying figures, theadjusting organs 49 are all arranged on the same support plate 41 so asto facilitate the access by an operator to the adjusting organs 49; inother words, if all the adjusting organs 49 are arranged on the samesupport plate 41, it is sufficient to allow an operator to access saidsupport plate 41 in order to act on all the adjusting organs 49.

The operation of the incision unit 20 is described below with referenceto FIGS. 5-8.

Firstly, the semirigid plastic material strip 15 is arranged at theincision devices 42 a (FIG. 5), i.e. is arranged between the incisiondevices 42 a. At this point and as shown in FIG. 6, the two supportplates 41 are approached each other by operating actuator 48, whichtranslates a support plate 41 along the rails 47 and in the incisiondirection I; such a relative movement between the two support plates 41leads the incision devices 42 a to cut the inner surface 8 of thesemirigid plastic material strip 15 (by approaching together thecorresponding cutting elements 43 and contrast elements 44) so as to cutthe inner incisions 7 (the incision devices 42 b also perform anincision movement, although without practical effects since thesemirigid plastic material strip 15 is not present between the incisiondevices 42 b).

Once the cutting of the inner incisions 7 into the inner surface 8 ofthe semirigid plastic material strip 15 has been completed, the supportplates 41 are brought back to their initial distance (FIG. 5); the twosupport plates 41 are then translated together by operating actuator 46so as to move the two support plates 41 laterally in the translationdirection T in order to invert the incision devices 42 coupled to thesemirigid plastic material strip 15. In other words, firstly theincision devices 42 a are coupled to the semirigid plastic materialstrip 15 (FIG. 5), whereas at the end of the lateral translation of thetwo support plates 41, the incision devices 42 b are coupled to thesemirigid plastic material strip 15 (FIG. 7).

At this point and as shown in FIG. 8, the two support plates 41 areapproached each other by operating actuator 48, which translates asupport plate 41 along the rails 47 and in the incision direction I;such a relative movement between the two support plates 41 leads theincision devices 42 b to cut the outer surface 10 of the semirigidplastic material strip 15 (by approaching together the correspondingcutting elements 43 and contrast elements 44) so as to cut the outerincisions 9 (the incision devices 42 a also perform an incisionmovement, although without practical effects since the semirigid plasticmaterial strip 15 is not present between the incision devices 42 a).

Once the cutting of the outer incisions 9 into the outer surface 10 ofthe semirigid plastic material strip 15 has been completed, the cycle ofthe incision unit 20 is completed and the semirigid plastic materialstrip 15 is fed from the conveying device 21 along the conveyingdirection C.

The semi rigid plastic material strip 15 does not move (i.e. isstationary in the same position) between the cutting of the innerincisions 7 into the inner surface 8 of the semirigid plastic materialstrip 15 and the cutting of the outer incisions 9 into the outer surface10 of the semirigid plastic material strip 15, since the incisiondevices 42 supported by the two support plates 41 perform a lateraltranslation; thereby, the incisions 7 and 9 have an almost perfectalignment with respect to each other since it is totally free frompossible errors due to the incorrect positioning of the semirigidplastic material strip 15.

As shown in FIG. 10, the dosing unit 26 comprises a tank 50 holding thefluid product 5 and three feeding ducts 27, each of which originatingfrom tank 50 and ending with a delivery mouth 51 which is arranged atthe longitudinal sealing device 23. A pump 52 is arranged along eachfeeding duct 27 so as to feed the fluid product 5 from tank 50 towardsthe delivery mouth 51.

Each pump 52 is a volumetric pump of peristaltic type (i.e. is aperistaltic pump) so as to provide for a precise dosing of product 5.According to a preferred embodiment, each peristaltic pump 52 has animpeller which supports a plurality of thrust elements (not less thanfour thrust elements and preferably eight thrust elements).

According to a preferred embodiment, tank 50 is pressurized at apressure which is higher than the atmospheric pressure; such a featureallows the suction of product 5 by the peristaltic pumps 52 to beenhanced thus avoiding the occurrence of “voids” along the feeding ducts27 and increasing the precision of dosing product 5. In particular, tank50 has at least one nozzle 53, which is arranged in an upper portion oftank 50 and is adapted to blow a compressed air jet into tank 50, whichkeeps the internal volume of tank 50 under pressure (i.e. pressurized).

According to a preferred embodiment, a shutoff valve 54 is included,which is arranged along each feeding duct 27 upstream of thecorresponding peristaltic pump 52. The shutoff valves 54 allow the flowof product 5 along the feeding ducts 27 to be stopped when the packagingmachine 11 is stopped (with the packaging machine 11 stopped and in theabsence of the shutoff valves 54, a small amount of product 5 wouldcontinue to flow by gravity along the feeding ducts 27).

The dosing unit 26 allows the fluid product 5 (in particular asanitizing gel) to be dosed with high precision (of the order of ±2-3%)even in the case of very small amounts (e.g. of the order of onemillimeter of fluid product in each single-dose package 1). Such aresult is also achieved, inter alia, by using peristaltic pumps 52 whichmaintain a high precision even in the case of low volumetric capacity.

The above-described packaging machine 11 has three production linesarranged one next to the other and operating in parallel; a differentnumber of production lines can obviously be provided as a function ofthe throughput required (e.g. a single production line or two, four ormore production lines).

In known packaging machines, dosing very small doses of fluid product(of the order of one millimeter of fluid product in each single-dosepackage) might result in a relatively low precision (with an error ofthe order of ±6-8%). To solve this problem, a dosing unit 26 may beused, comprising: a tank 50 holding a fluid product 5; at least onefeeding duct 27, which originates from tank 50 and ends with a deliverymouth 51; and a peristaltic pump 52 which is arranged along the feedingduct 27 so as to feed the fluid product 5 from tank 50 to the deliverymouth 51, where tank 50 is pressurized at a pressure which is higherthan the atmospheric pressure.

Preferably, tank 50 has at least one nozzle 53, which is arranged in anupper portion of tank 50 and is adapted to blow a compressed air jetinto tank 50. Preferably, the peristaltic pump 52 has an impeller whichsupports at least four thrust elements. Preferably, the peristaltic pump52 has an impeller which supports eight thrust elements. A shutoff valve54 is preferably provided, which is arranged along the feeding duct 27upstream of pump 52.

In known packaging machines, it has been noted that, when operating athigh speed, the pattern of the semirigid plastic material strip has notalways an optimal quality. In particular, the pattern might beincomplete, i.e. have some larger or smaller zones with no printing, dueto a non-optimal contact between a printing head of a printing deviceand the semirigid plastic material strip during the printing process. Inorder to improve the contact between the printing head and the semirigidplastic material strip, it has been suggested to decrease the distancebetween the printing device and a fixed contrast opposed to the printingdevice so as to increase the pressure with which the printing headpushes the semirigid plastic material strip against the contrast;however, such a solution might determine the occurrence of an excessivemechanical stress on the printing head, which stress might lead in ashort time to breakage of the printing head. In order to solve thisproblem, a printing unit 19 may be used, comprising: a conveying device33, which feeds strip 15 along a conveying direction C; a printingdevice 34 facing a first surface 10 of strip 15 so as to print a patternon strip 15; and a contrast plate 36, which is parallel to and faces theprinting device 34 so that strip 15 is arranged between the contrastplate 36 and the printing device 34, where the contrast plate 36comprises at least one nozzle 37, which opens up onto a second surface 8of strip 15 and is adapted to release a compressed air blow. Thecompressed air blown by nozzle 37 preferably creates a pressurized aircushion 38 at the second surface 8 of strip 15 opposite to the printingdevice 34. The contrast plate 36 preferably comprises a plurality ofnozzles 37 spaced apart from one another. Preferably, the printingdevice 34 is a heat transfer printing device. The printing device 34preferably comprises a printing head 35 which is movable along aprinting direction S orthogonal to the conveying direction C andorthogonal to strip 15. The compressed air is preferably fed to nozzle37 with a pressure from 2 to 6 bar. The compressed air is preferably fedto nozzle 37 with a pressure from 3 to 5 bar.

1. A unit for the incision of a strip made of a plastic material to cuttwo distinct incisions into two opposite surfaces of the strip in apackaging machine to manufacture a sealed single-dose break-openpackage; the incision unit comprises: a conveying device, which feedsthe strip along a conveying direction; two support plates, which arearranged on opposite sides of the strip, so that each support platefaces a corresponding surface of the strip; and at least two incisiondevices, each of which cuts an incision into a corresponding surface ofthe strip and comprises a cutting element, which is supported by asupport plate, and a contrast element, which is supported by the othersupport plate; wherein the two support plates are mobile so as totranslate together along a translation direction, which is orthogonal tothe conveying direction; wherein the two incision devices are arrangedone next to the other and are aligned along the translation direction;and wherein a first actuating device is provided, which cyclically movesthe two support plates forward and backward along the translationdirection between a first position, in which a first incision device isoperated so as to cut a first incision, and a second position, in whicha second incision device is operated so as to cut a second incision,which is opposite to the first incision.
 2. An incision unit accordingto claim 1, wherein each support plate supports the cutting element ofan incision device and the contrast element of the other incisiondevice.
 3. An incision unit according to claim 1, wherein each cuttingelement comprises a blade.
 4. An incision unit according to claim 3,wherein each blade is V-shaped and each contrast element is flat.
 5. Anincision unit according to claim 1, wherein each incision devicecomprises an adjusting organ, which is coupled to the cutting element orto the contrast element and adjusts the distance between the cuttingelement or the contrast element and the strip.
 6. An incision unitaccording to claim 5, wherein the adjusting organs are all arranged on asame support plate.
 7. An incision unit according to claim 1, wherein atleast one support plate is mobile so as to cyclically move forward andbackward, due to a second actuating device, towards the other supportlate and along an incision direction, which is perpendicular to thestrip and perpendicular to both the conveying direction and thetranslation direction.
 8. An incision unit according to claim 1, whereinthe conveying device comprises at least one feeding dandy roller, whichis arranged upstream of the support plates and is mobile so as to allowthe strip to temporarily stop between the two support plates.
 9. Apackaging machine to manufacture a sealed single-dose break-openpackage; the package consists of a first sheet made of a semirigidplastic material, which is arranged on top of and sealed to a secondsheet made of a flexible plastic material, so as to define a sealedpocket containing a dose of a product, and has a pair of incisions toguide a controlled breaking of the first sheet; the packaging machinecomprises: a first unwinding device to feed a first strip made of asemirigid plastic material; a second unwinding device to feed a secondstrip made of a flexible plastic material; an incision unit to cut twoincisions into the first strip made of a semirigid plastic material; aforming station, which is arranged downstream of the incision unit so asto arrange the first strip made of a semirigid plastic material on topof the second strip made of a flexible plastic material; a firstlongitudinal sealing device to longitudinally and laterally seal the twostrips to one another, so as to define at least one tube; a dosing unit,which is arranged in the forming station so as to feed a dose of aproduct into the tube between the first strip made of a semirigidplastic material and the second strip made of a flexible plasticmaterial; a second transverse sealing device, which is arrangeddownstream of the dosing device so as to transversely seal the twostrips to one another in order to define, along the tube, a series ofpockets, each containing a dose of product; and a cutting device, whichis arranged downstream of the forming station so as to transversely cutthe tube in order to separate, in sequence, the sealed single-dosepackages (1); wherein the incision unit is manufactured according toclaim
 1. 10. A method for the incision of a strip made of a plasticmaterial to cut two distinct incisions into two opposite surfaces of thestrip in a packaging machine to manufacture a sealed single-dosebreak-open package; the incision method comprises the steps of:conveying the strip along a conveying direction and between two supportplates, so that each support plate faces a corresponding surface of thestrip; cutting the strip by means of at least two incision devices, eachcutting an incision into a corresponding surface of the strip;translating the two support plates together along a translationdirection, which is orthogonal to the conveying direction; andcyclically moving the two support plates forward and backward along thetranslation direction between a first position, in which a firstincision device is operated so as to cut a first incision, and a secondposition, in which a second incision device is operated so as to cut asecond incision, which is opposite to the first incision.
 11. A methodfor the incision of a strip made of a semirigid material according toclaim 10, wherein the two incision devices are arranged one next to theother and are aligned along the translation direction.
 12. A method forthe incision of a strip made of a semirigid material according to claim10, wherein the strip made of a semirigid material is temporarilystopped during the strip incision step.
 13. A dosing unit of a packagingmachine for sealed single-dose packages; the dosing unit comprises: atank holding a fluid product; at least one feeding duct, whichoriginates from the tank and ends with a delivery mouth; and a pump,which is peristaltic pump and is arranged along the feeding duct so asto feed the fluid product from the tank to the delivery mouth; whereinthe tank is pressurized at a pressure that is higher than theatmospheric pressure.
 14. A dosing unit according to claim 13, whereinthe tank has at least one nozzle, which is arranged in an upper portionof the tank and is suited to blow a jet of compressed air into the tank.15. A dosing unit according to claim 13, wherein the peristaltic pumphas an impeller, which supports at least four thrust elements.
 16. Adosing unit according to claim 13, wherein the peristaltic pump has animpeller, which supports at least eight thrust elements.
 17. A dosingunit according to claim 13 and comprising a shut-off valve, which isarranged along the feeding duct upstream of the pump.
 18. A dosing unitaccording claim 13, wherein the fluid product is a sanitizer gel.
 19. Aunit to print a deformable plastic material strip of a packaging machinefor sealed single-dose packages; the printing unit comprises: aconveying device, which feeds the strip along a conveying direction; aprinting device, which is arranged in a fixed position along theconveying device and faces a first surface of the strip so as to print apattern on the strip; and a contrast plate, which is independent andseparate from the conveying device, is arranged in a fixed positionalong the conveying device, and is parallel to and faces the printingdevice so that the strip is arranged between the contrast plate and theprinting device; wherein the printing device comprises a printing head,which in use contacts the strip with a given pressure so as to print apattern on the strip; and wherein the contrast plate comprises at leastone nozzle, which opens up onto a second surface of the strip and issuited to release a blow of compressed air so as to create a pressurizedair cushion in correspondence to the second surface of the strip that isopposite to the printing device, said air cushion constitutes adeformable contrast against which the printing head pushes the strip.20. A printing unit according to claim 19, wherein the contrast platecomprises a plurality of nozzles that are spaced apart from one another.21. A printing unit according to claim 19, wherein the printing deviceis a heat transfer printing device.
 22. A printing unit according claim19, wherein the printing head is mobile along a printing direction,which is orthogonal to the conveying direction and orthogonal to thestrip.
 23. A printing unit according to claim 19, wherein the compressedair is fed to the nozzle with a pressure ranging from 2 to 6 bar.
 24. Aprinting unit according to claim 19, wherein the compressed air is fedto the nozzle with a pressure ranging from 3 to 5 bar.
 25. A method toprint a deformable plastic material strip of a packaging machine forsealed single-dose packages; the printing method comprises the steps of:conveying the strip along a conveying direction by means of a conveyingdevice; printing a first surface of the strip by means of a printingdevice, which is arranged in a fixed position along the conveying deviceand is coupled to a contrast plate, which is independent and separatefrom the conveying device, is arranged in a fixed position along theconveying device, and is parallel to and faces the printing device sothat the strip is arranged between the contrast plate and the printingdevice; wherein the printing device comprises a printing head, which inuse contacts the strip with a given pressure so as to print a pattern onthe strip; and releasing a blow of compressed air through a nozzle,which is obtained through the contrast plate and opens up onto a secondsurface of the strip so as to create a pressurized air cushion incorrespondence to the second surface of the strip that is opposite tothe printing device, said air cushion constitutes a deformable contrastagainst which the printing head pushes the strip.